The ever-growing use of photodetectors, in a wide range of both everyday and high-end applications, has flourished in the digital age. Excellent photodetection performance is realized with sensors integrated into complementary metal-oxide-semiconductor devices, and fabricated from semiconductors such as expensive, highly engineered crystalline silicon or biologically hazardous Cd-, Pb-, Hg- and As-based compounds. The development of efficient, environmentally benign, wavelength-tunable photoconductor materials can provide new applications in flexible, low-cost, lightweight and disposable photodetectors. Organics are naturally suited to meet these requirements. When used alone, however, organics are often susceptible to device degradation through charge trapping and photo-oxidation.
Achieving highly ordered nanostructured organic/inorganic hybrids in which both components contribute to overall functionality is critical for optimizing optoelectronic device performance1, 2. For example, to make highly sensitive polycrystalline photoconductors, it is necessary to maximize the density of long-lifetime trap states that enable photoconductive gain while minimizing transport noise associated with trap states at the interfaces between crystallites3, 4. Recent studies have shown that ultrasensitive photodetectors can be made from fused PbS nanoparticles, provided that their trap states do not exist at nanoparticle grain boundaries and disrupt their conductivity4, 5. Incorporating organic dyes into the network can offer extra benefits such as tuning the optical photoaction spectra and the lifetime of trap states with molecular structure. On photoexcitation, electrons are injected from the organic into the inorganic, with the remaining hole on the organic serving as a long-lifetime trap state. Optimum sensitivity is expected by controlling the assembly and nanostructure of the two components to maximize the density of organic dye bound to the surface of nanoparticles and to minimally disrupt conduction through the percolating network.
Many successful strategies have been developed that incorporate the interactions of a structure-directing organic to template ordered nanoscale morphologies of a conductive inorganic phase6, 7, 8, 9, 10, 11. In these examples, the organic is not electronically active and remains solely to maintain the overall nanostructure. An extension of these strategies is to remove and replace the structure-directing organic with functional organic components after templating12, 13. This provides little, if any, control over the order parameter in the functional organic phase because it does not participate in the mineralization process.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.